A series of small studies has suggested that human milk (HM) feedings protect very low birthweight (VLBW;birthweight <1500 g) infants from prematurity-specific morbidities that are costly and handicapping. However, no previous research has conclusively linked HM feedings with improved infant health outcomes and lowers neonatal intensive care unit (NICU) cost of care for this population, or has addressed whether longer and/or critical periods of exposure to HM feedings are necessary to achieve these beneficial outcomes. In the absence of this evidence, the costs of providing HM, most of which are borne by mothers rather than public and private insurers, serve as barriers to the initiation and maintenance of lactation for mothers of VLBW infants, who are disproportionately likely to be low-income and African American. The overall objective of this 5-year study is to examine the relationship between the independent variables of dose and exposure period of HM feedings, and the dependent variables of infant health outcomes and cost savings of HM feedings for VLBW infants throughout their stay in the neonatal intensive care unit (NICU). The proposed project will follow a prospective cohort of 600 VLBW infants born to racially and economically diverse mothers (40 percent African American;40 percent non-Hispanic Caucasian;20 percent Hispanic;60 percent low-income) throughout the NICU stay to test 3 major hypotheses: that higher doses and longer and/or critical periods of exposure to HM feedings are associated with 1) a lower relative risk of mortality and prematurity-specific morbidities;2) shorter length of NICU stay and appropriate infant growth;and 3) lower total NICU costs. Eligible infants and their mothers who consent to participate in the study will be enrolled upon the infant's admission to the NICU. Data addressing the independent variables of dose and exposure period of HM feedings will be collected electronically for each enteral feeding throughout the infant's entire NICU stay. Data addressing the dependent variables of infant health outcomes and costs will be collected electronically at regular intervals, and will include the short-term costs of providing HM, such as breast pump rental, number of HM storage containers, and access to lactation experts, as well as total NICU health care costs. Statistical analyses will include structural equation modeling, risk analysis, multiple regression analysis, and cost-effectiveness analysis. Significance: This research is the first prospective study to examine the relationship between dose and exposure period of HM feedings and infant health outcomes and costs of HM feedings, for a large sample of VLBW infants born to representative numbers of African American and low-income women. The findings from this study will translate readily into health policy and NICU protocols for this vulnerable population. Project Narrative Relevance: This research is the first prospective study to examine the relationship between dose and exposure period of HM feedings and infant health outcomes and costs of HM feedings, for a large sample of VLBW infants born to representative numbers of African American and low-income women. The findings from this study will translate readily into health policy and NICU protocols for this vulnerable population.